distribution amplifier (type 887)
This is housed in a
"utility" box with looping inputs and six outputs (video plus two audio).
This DA operates on AC mains (150 to 250v without adjustment), and has
no external controls except a video terminating switch. You may have come
across its predecessor (DA-282) which Andrew designed originally for the
set-up of Chroma Video (where he was Engineering Director), and was then
sold by Johannesburg Video (later Avvid) - it must since then have become
the most "pirated" video design in SA! This unit is in use in many TV facilities
throughout the country, and has spawned a number of derivatives offering
alternative facilities (component video etc.).
and Audio distribution amplifiers (type 189 video and 988 audio)
These rack-mounted modules
(similar in concept to the Avitel range) have 6 or 8 outputs each. Video
DA's have built-in gain/EQ adjustment plus selection of composite/non-composite/average
level DC restoration. Up to 16 modules may be mounted in a 3U 19-inch rack
frame - two modules may be replaced by a power supply module (type 890).
Provision is made to install two PSU's in one rack, or to interconnect
racks enabling "redundant" supply operation for optimum reliability. These
units are in use in a number of locations throughout the country (Six Street
Studios, both Johannesburg and Cape Town, Trilion, ZSE-TV, Trinity Broadcasting,
Video Cassette Reproductions, Kinnor Centre, Video Duplications, Camera
Video/Audio matrix (type 884)
This is a modular "industrial"
design with options for mono or stereo, balanced or unbalanced audio, etc.
Variations are in use in many duplicating facilities (ZSE-TV, Video Lab,
VCR, CopyVision, etc.) and educational/broadcast facilities (Wits, Bop-TV,
matrix (separate video and audio frames, each 6U)
A professional unit
with standard "double Eurocard" PCB's, gain/EQ adjustment on each video
output, balanced audio, etc. Control is by a parallel data bus operated
by computer or manual panel(s) as required.
(up to 150-input in a 3U frame) for video or audio
A "professional" modular
style with "Eurocard" PCB's, gain/EQ adjustment, audio level adjustment,
Again, separate frames
for video and audio (each one 3U).
We have designed and
manufactured special purpose switchers (e.g. for component
video or for computer R-G-B applications), as well as video pattern
generators, keyers etc. for specific customer applications.
For ease of maintenance
the designs have all active circuitry on plug-in printed circuit boards
- these may be of the "Eurocard" type (i.e. front panel access) in the
"professional" designs, or accessible by removing a cover in the cheaper
"industrial" designs. Please note that all components used are bought locally
and (with a few minor exceptions) are multiple-sourced. No difficult-to-get
(or even difficult-to-see!) special integrated circuits, surface mount
components etc. are used, so it is not necessary to worry about spares
holdings, sophisticated test equipment, or long down-times in the unlikely
event of a fault developing.
Whilst the basic requirements
for video and audio routing systems are well known, note that we are able
to customise a large number of options. These include:-
Overall system complexity
and cost can be significantly reduced by some or all of these "extra" facilities
being incorporated within a single structure instead of being added externally.
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stereo/mono audio (or additional channels for timecode, control etc.)
adjustable input levels (where source output levels cannot be normalised)
adjustable output levels (where destination input levels cannot be normalised)
selection of clamped or restored video DC output levels
adjustable cable equalisation for video outputs
balanced or unbalanced audio inputs/outputs
terminated or loop-through video inputs
additional buffered outputs
input/output connector types as required
etc., etc. ...